The present invention relates to machine tools in general, and more particularly to improvements in multiple-spindle automatic machines of the type wherein a carrier is indexible in the frame of the machine and supports several equally spaced rotary work spindles.
In presently known multiple-spindle automatic chucking or bar machines the frame supports several cross slides for various tools which are used for radial treatment of workpieces. The cross slides are installed in front of the frame member which supports the spindle carrier. The material removing operations lengthwise and at the front ends of the workpieces are carried out by tools which are mounted on a main support extending substantially axially of the spindle carrier. The carriages for tools which are used for lengthwise and front treatment of workpieces are movable along the main support toward or away from the front side of the spindle carrier. It is also known to fixedly mount the tools on the main support and to feed the main support axially of the spindle carrier.
The just described types of multiple-spindle machines are normally used for treatment of large numbers of relatively short workpieces. They are much less suited, or totally unsuited, for the treatment of relatively long workpieces because each workpiece is clamped and held only at one of its ends and the major part of the workpiece remains unsupported. The provision on the main support of a device having means for engaging the free ends of elongated workpieces which extend beyond the chucks or collets of the work spindles would be of little help because such device would interfere with lengthwise movement of the main support and/or with lengthwise movement of tool carriages on the main support. In other words, by mounting the free ends of elongated workpieces on a member which is carried by the main support, one would have to dispense with the longitudinally movable tool carriages so that the workpieces could be treated only by tools which are mounted on the cross slides adjacent to the front face of the spindle carrier.
It is further known to employ in single-spindle machines a pair of work-engaging devices which may constitute chucks, collets or centers. Such machines exhibit a highly desirable versatility; however, their output is only a small fraction of the output of a multiple-spindle machine, even if their operation is fully automatic.